Swing motion reducing apparatus for ship

ABSTRACT

In a swing motion reducing apparatus for a ship includes a flywheel, a gimbal mechanism configured to rotatably support the flywheel, a motor configured to rotate the flywheel based on a drive power to be supplied; and a motor driver configured to supply the drive power to the motor. A damper section is configured to brake a swing motion of the gimbal mechanism. A safety unit controls the motor driver to stop the supply of the drive power to the motor when a temperature of the damper section is equal to or higher than a predetermined temperature.

INCORPORATION BY REFERENCE

This patent application claims a priority on convention based onJapanese Patent Application No. 2009-103158. The disclosure thereof isincorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an apparatus for reducing a swingingmotion of a ship such as a rolling motion, a pitching motion and ayawing motion.

2. Description of Related Art

Japanese Patent No. 3,556,857 discloses a swinging motion reducingapparatus for reducing rolling, pitching and yawing motions of a ship.The swinging motion reducing apparatus includes a motor, a flywheel thatis driven by the motor, a gimbal mechanism that contains the flywheel, asupport section for movably supporting the gimbal mechanism, africtional damper for controlling a motion of the gimbal mechanism, apower supply for supplying electric power to the motor, and a controlsection. When the gimbal mechanism rolls at a predetermined angle ormore, the control section controls such that the power supply to themotor is stopped to prevent the swinging motion reducing apparatus frombeing damaged because of the motion of the gimbal mechanism exceeding alimitation of the specification.

SUMMARY OF THE INVENTION

An object of the present invention is to prevent a swinging motionreducing apparatus for a ship from being damaged.

In an aspect of the present invention, a swing motion reducing apparatusfor a ship includes a flywheel, a gimbal mechanism configured torotatably support the flywheel, a motor configured to rotate theflywheel based on a drive power to be supplied; and a motor driverconfigured to supply the drive power to the motor. A damper section isconfigured to brake a swing motion of the gimbal mechanism. A safetyunit controls the motor driver to stop the supply of the drive power tothe motor when a temperature of the damper section is equal to or higherthan a predetermined temperature.

According to the present invention, damage of a swinging motion reducingapparatus for a ship is prevented.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram schematically showing a swinging motion reducingapparatus for a ship according to a first embodiment of the presentinvention;

FIG. 2 is a cross-section view of the swinging motion reducing apparatusbody; and

FIG. 3 is a diagram schematically showing the swinging motion reducingapparatus according to a second embodiment of the present invention.

DESCRIPTION OF THE EMBODIMENTS

Hereinafter, a swinging motion reducing apparatus for a ship accordingto the present invention will be described with reference to theattached drawings.

First Embodiment

As shown in FIG. 1, a swinging motion reducing apparatus according to afirst embodiment of the present invention includes a swinging motionreducing apparatus body 10, a motor driver 20, a generator 30, and asafety unit 40. The swinging motion reducing apparatus body, 10 includesa motor 13, a damper 15A, and a damper 15B. The generator 30 and themotor 13 are a 3-phase generator and a 3-phase motor, respectively. Themotor driver 20 includes an input terminal 21, an output terminal 22, aCM terminal 23, an X1 terminal 24, and a relay 25. The input terminal 21includes an R terminal, an S terminal, and a T terminal. The outputterminal 22 includes a U terminal, a V terminal, and a W terminal. Therelay 25 is provided between the input terminal 21 and the outputterminal 22. The relay 25 opens and closes a connection between the Rterminal and the U terminal, a connection between the S terminal and theV terminal, and a connection between the T terminal and the W terminal.The input terminal 21 is connected to the generator 30 via a breakerswitch 31. The output terminal 22 is connected to a power cable 13 a ofthe motor 13.

The safety unit 40 includes a bimetal switch 41A provided for the damper15A and a bimetal switch 41B provided for the damper 15B. The bimetalswitches 41A and 41B are in a close state initially, and monitortemperatures of the dampers 15A and 15B, respectively. The bimetalswitch 41A opens to set an OFF state when a temperature of the damper15A increase to a temperature equal to or higher than a predeterminedtemperature. The bimetal switch 41B opens to set an OFF state when thetemperature of the damper 15B increase to a temperature equal to orhigher than a predetermined temperature. The CM terminal 23 is connectedto the X1 terminal 24 via the bimetal switches 41A and 41B. Since thebimetal switches 41A and 41B are connected to each other in series, theconnection between the CM terminal 23 and the X1 terminal 24 is in an ONstate (a conduction state) when both of the bimetal switches 41A and 41Bclose, and the connection between the CM terminal 23 and the X1 terminal24 is in an OFF state (a non-conduction state) when at least one of thebimetal switches 41A and 41B opens.

The relay 25 turns the connection between the input terminal 21 and theoutput terminal 22 to be in the ON state (closes the connection betweenthe input terminal 21 and the output terminal 22) when the connectionbetween the CM terminal 23 and the X1 terminal 24 is in the ON state.Also, the relay 25 turns the connection between the input terminal 21and the output terminal 22 to be in the OFF state (opens the connectionbetween the input terminal 21 and the output terminal 22) when theconnection between the CM terminal 23 and the X1 terminal 24 is in theOFF state.

The motor driver 20 supplies a drive power to the motor 13 when therelay 25 keeps the connection between the input terminal 21 and theoutput terminal 22 in the ON state, and stops the supply of the drivepower when the relay 25 turns the connection between the input terminal21 and the output terminal 22 to be in the OFF state.

As shown in FIG. 2, the swinging motion reducing apparatus body 10includes the flywheel 11, the gimbal mechanism 12, the motor 13, agimbal mechanism support section 14, and the dampers 15A and 15B. Thegimbal mechanism 12 supports the flywheel 11 so that the flywheel 11 canrotate around a rotation axis S1. The motor 13 drives the flywheel 11.The gimbal mechanism support section 14 supports the gimbal mechanism 12so that the gimbal mechanism 12 can swing around a swing axis S2. Eachof the dampers 15A and 15B brakes the swinging motion of the gimbalmechanism 12 with a fluid resistance of a hydraulic oil. For example,the dampers 15A and 15B are rotary dampers. The swing axis S2 isorthogonal to the rotation axis S1. The gimbal mechanism support section14 is fixed to a hull. The bimetal switches 41A and 41B are attached tothe outer sides of the dampers 15A and 15B, respectively.

A principle that the swinging motion reducing apparatus according to thepresent embodiment reduces the swinging motion of a ship will bedescribed by exemplifying a case that a left or right direction axis(Pitch axis) of the hull is parallel to the swing axis S2. The flywheel11 is driven by the motor 13 at a high speed so as to have angularmomentum H. When the hull receives a wave in a direction of a roll axisto roll at an angular velocity Ω, a gyrotorque T1 represented by anexterior product of the angular momentum H and the angular velocity Ωacts to the gimbal mechanism 12, and the gimbal mechanism 12 rollsaround the swing axis S2. At this time, since the flywheel 11 works tomaintain the angular momentum H, a counter torque T2 acts to the hullvia the gimbal mechanism support section 14. When an angular velocity ofthe swinging motion of the gimbal mechanism 12 is ω, the counter torqueT2 is represented by an exterior product of the angular momentum H andthe angular velocity ω. Because the counter torque T2 acts to adirection opposite to the roll direction of the hull, the rolling motionin the roll direction of the hull is reduced.

For example, when the swinging motion reducing apparatus is used underan overload circumstance such as a case where a ship having the swingingmotion reducing apparatus according to the present embodiment sails ahigh wave area, the gimbal mechanism 12 heavily swings so that thetemperatures of the dampers 15A and 15B become high, and thus a sealmember for sealing the hydraulic oil may be damaged. Since the gimbalmechanism 12 cannot be broken when the hydraulic oil leaks, the swingingmotion reducing apparatus may be damaged.

Referring to FIG. 1, when the temperature of the damper 15A increasesthe predetermined temperature or more, the bimetal switch 41A opens toturn the connection between the CM terminal 23 and the X1 terminal 24 tobe in the OFF state. Then, since the relay 25 turns the connectionbetween the input terminal 21 and the output terminal 22 to be in theOFF state, the motor driver 20 automatically stops the supply of thedrive power. Also, when the temperature of the damper 15B increases thepredetermined temperature or more, the motor driver 20 automaticallystops the supply of the drive power in the same manner as that of thedamper 15A. That is, the safety unit 40 stops the supply of the drivepower to the motor driver 20 when at least one of the dampers 15A and15B exceeds the predetermined temperature. In this manner, the swingingmotion reducing apparatus body 10 safely stops and the dampers 15A and15B can be prevented from being damaged.

Additionally, in case of occurrence of a failure of the damper 15A or15B, the temperatures of the damper 15A or 15B becomes high. The presentembodiment prevents the swinging motion reducing apparatus fromcontinuing to operate under the condition of occurrence of the failureof the damper 15A or 15B. Accordingly, the damage of the damper 15A or15B can be prevented and the damage of the swinging motion reducingapparatus body 10 is prevented.

Moreover, when an atmosphere temperature around the swinging motionreducing apparatus body 10 is high, the damper 15A or 15B cannot releasethe heat to circumference, and accordingly a braking performance of thedamper 15A or 15B deteriorates. When the swinging motion reducingapparatus continues to operate in a state that the braking performanceof the damper 15A or 15B deteriorates, the swinging motion reducingapparatus body 10 may be damaged. According to the present embodiment,since the swinging motion reducing apparatus is stopped in the case of ahigh atmosphere temperature, the damage of the swinging motion reducingapparatus body 10 can be prevented.

Since the bimetal switches 41A and 41B are respectively arranged on theouter sides of the dampers 15A and 15B, the swinging motion reducingapparatus can be easily assembled. Meanwhile, the bimetal switches 41Aand 41B may be arranged in the dampers 15A and 15B, respectively.

Second Embodiment

Referring to FIG. 3, the swinging motion reducing apparatus for a shipaccording to a second embodiment of the present invention will bedescribed. The swinging motion reducing apparatus according to thesecond embodiment of the present invention is configured by replacingthe safety unit 40 in the first embodiment with a safety unit 50. Thesafety unit 50 includes temperature sensors 51A and 51B such as athermocouple or a thermistor, and a determining section 52. Thetemperature sensors 51A and 51B are provided for the dampers 15A and15B, respectively. The temperature sensor 51A monitors a temperature ofthe damper 15A and outputs a signal indicating the temperature of thedamper 15A to the determining section 52. The temperature sensor 51Bmonitors a temperature of the damper 15B and outputs a signal indicatingthe temperature of the damper 15B to the determining section 52. Thedetermining section 52 is connected to the CM terminal 23 and the X1terminal 24, respectively. The determining section 52 determines whetheror not the temperatures indicated by the signals sent from thetemperature sensors 51A and 51B are higher than a predeterminedtemperature. When both of the signal sent from the temperature sensor51A and the signal sent from the temperature sensor 51B indicate atemperature lower than the predetermined temperature, the determiningsection 52 turns the connection between the CM terminal 23 and the X1terminal 24 to be in the ON state. When the temperature indicated by atleast one of the signal sent from the temperature sensor 51A and thesignal sent from the temperature sensor 51B exceeds the predeterminedtemperature, the determining section 52 turns the connection between theCM terminal 23 and the X1 terminal 24 to be in the OFF state.Accordingly, when at least one of the dampers 15A and 15B exceeds thepredetermined temperature, the safety unit 50 stops the supply of thedrive power to the motor 13.

When the temperature sensors 51A and 51B are arranged on the outer sidesof the dampers 15A and 15B, the swinging motion reducing apparatus canbe easily assembled. Meanwhile, the temperature sensors 51A and 51B maybe arranged in the dampers 15A and 15B, respectively.

In the above-mentioned respective embodiments, the generator 30 and themotor 13 may be a single-phase generator and a single-phase motor,respectively. In addition, the dampers 15A and 15B may be a frictionaldamper, a linear damper, or a hydraulic pump.

1. A swing motion reducing apparatus for a ship comprising: a flywheel;a gimbal mechanism configured to rotatably support said flywheel; amotor configured to rotate said flywheel based on a drive power to besupplied; a motor driver configured to supply the drive power to saidmotor; a damper section configured to brake a swing motion of saidgimbal mechanism; and a safety unit configured to control said motordriver to stop the supply of the drive power to said motor when atemperature of said damper section is equal to or higher than apredetermined temperature.
 2. The swing motion reducing apparatusaccording to claim 1, wherein said motor driver comprises first andsecond terminals, wherein said safety unit comprises a path from saidfirst terminal to said second terminal, and said motor driver suppliesthe drive power to said motor when said path is in an ON state, andstops the supply of the drive power to said motor when said path is inan OFF state.
 3. The swing motion reducing apparatus according to claim2, wherein said damper section comprises a first damper configured tobrake the swing motion of said gimbal mechanism, said safety unitcomprises a first bimetal switch provided for said first damper in saidpath, and said first bimetal switch sets said path to the ON state whenthe temperature of said first damper lower than the predeterminedtemperature and sets said path to the OFF state when the temperature ofsaid first damper equal to or higher than the predetermined temperature.4. The swing motion reducing apparatus according to claim 3, whereinsaid damper section comprises a second damper configured to brake theswing motion of said gimbal mechanism, wherein said safety unit furthercomprises a second bimetal switch provided for said second damper insaid path and connected with said first bimetal switch in series, andsaid second bimetal switch sets said path to the ON state when thetemperature of said second damper lower than the predeterminedtemperature and sets said path to the OFF state when the temperature ofsaid second damper equal to or higher than the predeterminedtemperature.
 5. The swing motion reducing apparatus according to claim2, wherein said damper section comprises first and second dampers, eachof which brakes the swing motion of said gimbal mechanism; said safetyunit further comprises: first and second temperature sensors providedfor said first and second dampers to detect temperatures of said firstand second dampers, respectively; and a determining section sets saidpath to the ON state, when both of temperatures detected by said firstand second temperature sensors are lower than the predeterminedtemperature, and sets said path to the OFF state, when at least one oftemperatures detected by said first and second temperature sensors isequal to or higher than the predetermined temperature.